Stiffened fabrics



Patented Feb. 27, 1945 STIFFENED FABRICS Alfred A. Lawrence, Port Chester, N. Y., and

Shaller L. Bass, Midland, Mich assignors to The Dow Chemical Company, Midland, Mich., a corporation of Michigan No Drawing. Application May 2, 1942, Serial No. 441,556

4 Claims. (Cl. 154-2) This invention relates to the preparation of stiffened fabrics, and particularly of stiifened textile fabrics which are permeable to air and moisture and which have-improved resistance to wear.

Resistance to wear is of great importance in many textile fabric articles such as certain parts of wearing apparel. For example, the collars and cuffs of shirts are subject to unusually hard wear and are generally the first part of the garment to become frayed. One method which has been used in attempting to overcome this difilculty has been to make the parts subject to excessive wear of a harder woven and better wearing fabric than the rest of the article. This procedure has met with some success in the case of undyed articles or garments, but the difficulty of dyeing fabrics of different materials or of different weave to the same shade does not ordinarily permit colored garments to be made in this way. Multiply fabrics have also been used extensively for making articles or parts thereof which are subject. to extensive wear.

Multi-ply fabrics used in making wearing apparel are usually treated to stiffen them somewhat and to cement or bond the separate layers of fabric together. It is desirable that the multiply fabric should not be crlnkly or have a papery feel or be unduly hard and that it "be resistant to laundering. It should also be possible, by ironing the laundered fabric, to restore it to its original texture and handle. Such stiffened multi-ply textile fabrics are usually made byplacing an interliner comprising a cementitious composition between layers of the fabric and hot-press ing to form a stiffened assembly. The interliner may be made by impregnating a layer of fabric with a flexible thermally cementitious plastic or resin, or it may be cut from a woven composition composed entirely or in part of filaments of the thermally cementitious plastic material. Some of the adhesive compositions used are first energized by treating with a solvent and are then hotpressed, while others, depending upon the composition of the particular material used, require only the application of heat and pressure. Multi-ply stiffened fabrics produced by the hitherto known processes are substantially nonpermeable to air and moisture and in many instances, after the multi-ply fabric has been constructed, it has been necessary to give it a separate surface finishing treatment in order to improve its handle and appearance and to give it customer appeal. 7

Many of the stifiening and finishing treatments so applied have been nonpermanent and have appearance, and which retains these properties after repeated laundering.

According to the invention a multi-ply structure of a textile fabric is formed, the plies being separated by insertion of a of a water-insoluble thermoplastic cellulose ether. This structure is treated with a substantially saturated solution of a water-insoluble cellulose ether in a mixture of a water-soluble organic solvent for th ether and water in amount insumcient to precipitate the ether from the solution. The action of the solution causes swelling of the cellulose ether mm, while the solution also impregnates the plies of fabric. When the structure has been thoroughly wet by the solution, it is removed, and then treated with a liquid, such as water. which precipitates the cellulose ether from the solution that remains in the fabric. Thereupon the treated fabric is dried and hotpressed to form a smooth on the fabric. By such treatment a stiffened fabric is produced of pleasing appearance and handle, which is durable in service, and is permeable to air and moisture. The invention may also be applied to the formation of single layers of stiffened fabric, in which case the procedure is the same as in the case of a multi-ply structure, except, of course, the cellulose ether film, is not employed.

Although the cellulose ether film used as an interliner between the layers of fabric may be made from any water-insoluble thermoplastic cellulose ether which is strongly swelled by the aqueous solution with which the structure is subsequently treated, it is preferably made from ethyl cellulose. Ethyl cellulose having an ethoxy content greater than per cent, and preferably between about 47.5 and about 49 per cent, has been used with success. Although the thickness of the film which is used depends to some extent upon the nature and thickness of the fabric used, films having a thickness up to 3 mils have'been used advantageously. Films having a thickness between about 1 and about 1.5 mils are usually '5, preferred. The film may also contain plasticizsired, and may be made by any of the usual processes for making such cellulose ether films.

The solution with which the composite structure is treated and which serves to swell the thermoplastic film and to impregnate the layers of fabric usually, but not necessarily, contains the same cellulose ether as that from which the thermoplastic film is made. Thus, if an ethyl cellulose film is used as an interliner between the layers of fabric, the treating solution may conveniently contain ethyl cellulose alone or mixed with other cellulose ethers. The treating solu tion may, if desired, contain any of the usual plasticizers or modifying agents for cellulose ethers which are soluble in the solution. The proportions of water and cellulose ether solvent may be varied over a wide range and may be adjusted so as to control th swelling of the cellulose ether film between the layers of fabric to any.

desired degree. Sufiicient cellulose ether is incorporated in the treating solution substantially to saturate it therewith; since by using such a solution, the cellulose ether film is readily softened and swelled, 'but substantially none of it is dissolved. The use of treating solutions which are relatively unsaturated with, or which contain no dissolved cellulose ether, are apt to dissolve rapidly the thin sections of cellulose ether film 'between the layers of fabric rather than to merely soften and swell them, thus making the process difficult to control in operation. Examples of water-soluble organic olvents for cellulose ethers which may be used in making up the treating solution include methanol, ethanol, propanol, acetone, methyl ethyl ketone, and many others. The solution may be prepared conveniently by dissolving the cellulose ether in the organic solvent and radually adding thewater thereto. When the solution is properly prepared, the addition of further appreciable amounts of water will cause a portion of the cellulose ether to separate from the solution. Although, as pointed out previously, the ratio. of water to cellulose ether solvent in the treating solution may be varied over wide limits, it has been found-that films of ethyl cellulose may be advantageously treated with solutions of ethyl cellulose in aqueous ethanol containing from 20 to 60 per cent by weight of waterbased. 0n the amount of ethanol present. It is apparent that the use of films of other water-insoluble thermoplastic cellulose ethers or of ethyl cellulose of ethoxy content outside of the preferred range previously mentioned may require the use of other water-soluble solvents, and it may be advisable to use these in proportions different from that indicated above for ethanol.

The treatment of the multi-ply structure with the treating solution is conveniently carried out in continuous manner by passing the structure through a bath of the solution. The length of time for which the structure remains in the solution is dependent upon a number of factors, including the composition and thickness of the particular cellulose ether film used, the degree of swelling of the film desired, the proportion of cellulose ether solvent in the solution, the temperature, etc. Usually, however, sufilcient swelling of the film is obtained in from 0.1 to 5 minutes. Although higher or lower temperatures may be employed, the multi-ply structure is usually treated with the solution at ordinary room. temperatures. The multi-ply structure may, if desired, be padded or otherwise manipu- 2,370,550 ers, resins, modifying agents and the like, if delated during its passage through the solution in order to assist penetration of the solution be-.

tween the plies. During this treating process, the fabric becomes solution.

The wet multi-piy structure is removed from the cellulose ether solution and treated with an agent, usually water, in either the liquid phase or in the vapor phase as steam, to precipitate the cellulose ether which is contained in the solution remaining in the structure. The precipitation may be carried out at ordinary or somewhat elevated temperatures, as desired, and is usually accomplished by passing the structure through a bath of water at ordinary temperatures or by steaming it at atmospheric or slightly elevated pressures. By precipitating the ethyl cellulose from the solution in this manner, the fibers of .which the fabric is composed are thoroughly impregnated with the ether in water-insoluble form. After thoroughly washing with water to remove the cellulose ether solvent, the structure is usually at least partially dried by squeezing or by blowing warm air over it and is then subjected to heat and pressure between plates or rolls. Such heat and pressure treatment serves to complete the drying operation and to permanently bond the successive layers of fabric together.

Although the temperature and pressure used de-- pend to some extent on the thickness of the structure and the proportion of water remaining therein and on the particular cellulose ether employed, advantageous results have been obtained by heating three-ply structures containing ethyl cellulose as the bonding agent to from to 185 C. under a pressure of from 60 to 100 pounds per square inch and for from 5 to 20 seconds.

The cellulose ether film and the precipitated cellulose ether, each of which is in a greatly swollen condition, are apparently largely absorbed by the fibers during the hot-pressing operation, thus'forming a relatively open, porous, unitary structure permeable to air and moisture. In addition to the bonding effect of the cellulose ether films between the fabric plies, the ether which is precipitated from the solution between and within the fibers of the plies of fabric serves to give the finished structure a pleasing, wearresistant finish which adds greatly to its appearance and utility. This is in great contrast to multi-ply structures which are formed by the ordinary method of simply hot-pressing together alternate layers of fabric and unswollen thermoplastic cellulose ether films or impregnated fabric interliners. Structures formed by the latter method are usually" impervious to air and moisture and do not have a pleasant feel or handle. The following examples serve to illustrate the practice of the invention but are not to be construed as limiting the scope thereof:

EXAMPLE 1 Two outer plies of poplin, an inner ply of lawn, and two sections of ethyl cellulose film were sewn together to form an assemblage consisting of alternate layers of fabric and film. A solution was prepared by dissolving 10 parts by weight of ethyl cellulose in 70 parts of ethanol and finally adding 30 parts of water. The assemblage was padded through the solution until thoroughly saturated, removed and immersed in water. After washing thoroughly with water and squeezing between mangle rolls to remove a portion of the water, the damp assemblage was subjected between metal plates to a temperature of C.

saturated with the cellulose ether v sistant to wear.

and a pressure of 100 pounds per square inch until thoroughly dry. The stiffened fabric thus obtained consisted of an integrally bonded multiply structure permeable to air and moisture and having a smooth surface finish. The stiffness and finish were retained after repeated laundering and pressing and the fabric was very re- EXAMPLE 2 A solution was prepared by dissolving 7.0 grams of ethyl cellulose. and 3.0 grams of a di-orthoxenyl mono-phenyl phosphate plasticizer in 65 grams of ethanol and adding grams of water.

A piece of cotton shirting (thread count 136/60) was padded through this solution, passed through squeeze rolls to remove excess solution, passed, through a water bath, again squeezed and hotpressed, The finished fabric was cut into sections and separate sections were subjected to wear tests after repeated washings. The sections were washed for 30 minutes in a 1 per cent soap solution at 60 to 65 C., rinsed for 5 minutes in warm water, partially air dried, and ironed until dry.

The washing process was then repeated a prede termined number of times. The wear tests were made on a Durfee Crock Meter similar to that described in the Year Book of the American Association of Textile Chemists and Colorists, vol. 16,

pp. 197-201 (1939) and fitted with a stroke counter. The tests were performed with patches of the cloth to be tested, both on the peg and in the usual place for the sample. Two tests were carried out on each cloth sample, one by stroking in the warp direction and the other by stroking in the weft direction of the fabric. The results are listed in the accompanying table. The results obtained during the wear test on an untreated and unwashed section of the original cloth are included in the table by way of comparison.

Tests:

of the cellulose ether in the treating solution. If desired, plasticizers may beincorporated in the padding solution orin the cellulose ether film Results of wear tests on treated fabric after repeated washings N o. of strokes to produce failure No. of times washed Well.

13 Untreated and unwashed fabric The stiffness of the multi-ply fabric prepared according to the present invention may be regulated as desired by using water-insoluble thermoplastic cellulose ether films of different thicknesses, by using a fewer or a greater number of plies of fabric, or by adjusting the concentration tion and the stiffened fabric is permeable to .air

and moisture; the thermoplastic material precipitated from the treating solution upon and between the fibers contributes a surface finish tothe fabric upon hot-pressing which adds materially to its appearance and handle and which eliminates the necessity of a separate finishing treatment.

The stiffened fabric prepared by the method ofthe invention is of particular value in the manufacture of collars, cufls, neckbands, shirt fronts. cap visors, and other portions of wearing apparel subject to excessive wear.

We claim: 1

1. The method for making a multi-ply stiffened fabric, characterized by its permeability to air and moisture, by a pleasing handle and appearance and by its resistance to wear after repeated laundering, which includes: forming a dry assemblage of a plurality of sheets of cloth fabric wherein each sheet is separated from each adjoining sheet by a preformed water-insoluble thermoplastic film comprising a cellulose ether; wetting the dry assemblage with, a liquid swellin agent for the cellulose ether film, said swelling agent having substantially no solvent action on said film and comprising a substantially saturated solution of a water-insoluble thermoplastic cellulose ether in a mixture of a water-soluble solvent therefor and water; treating the wet assemblage, after the cellulose ether film has been swollen to a predetermined degree, with water whereby the swelling of the cellulose ether film is arrested and the dissolved cellulose ether contained in the liquid swelling agent adhering to the assemblage isprecipitated; and subjecting the water-wet assemblage to heat and pressure.

2. The method as claimed in claim 1 wherein the cellulose ether film comprises ethyl cellulose.

The method as claimed in claim 1 wherein the swelling agent comprises a substantially saturated solution of ethyl cellulose.

4. The method as claimed in claim 1 wherein at least a portion of the water is removed from the water-wet assemblage before it is subjected to heat and pressure.

' A. LAWRENCE.

SHAILER L. BASS. 

